It has been a staple of our understanding of the processes behind human dexterity
for decades, that the faster you push at something, the more force you exert.
Now, it seems that is not actually accurate.

A research team led from the University of Southern California has reported
strange results in the Journal of Neuroscience.

The researchers set up a simple experiment to characterise how finger velocity
made a difference in the force produced during the common manipulation task
similar to rubbing a surface, using a computer track pad or iphone. Adult volunteers
wearing a closefitting Teflon cover on their forefingers applied fingertip pressure
on a slippery Teflon surface linked to a force-measuring sensor.

"As expected, maximal downward force diminished when motion was added
to the task," the researchers wrote. "But remarkably, there were no
significant differences between slow, and fast movement speeds
even though the movement speeds varied 36-fold."

The report goes on to strip away potential reasons for skewed data, one at
a time, including differing levels of dexterity by the subjects, non-linear
responses by muscles, and finger-muscle asymmetries. With all ruled out, the
only explanation left, is that physiological "force-velocity" properties
weaken muscles as they move faster.

"That is why your bicycle has gears, and why as a child you could not
speed up much on level ground," explained Valero-Cuevas, one of the authors
of the study and who holds a joint appointment in the USC Viterbi School of
Engineering's department of biomedical engineering and the USC Division of Biokinesiology
and Physical Therapy.

The implications for haptic control systems, and artificial replication of
force projection are quite profound, as it appears there are finite limits to
force exerted by the muscles of the human body, regardless of the speed at which
they are moving.